The growth of the Internet, social networking and mobile technologies has transformed how Americans communicate and exchange information, but Congress has lagged in updating federal privacy laws to safeguard digital communications from inappropriate prying. Late last month, the Senate Judiciary Committee made some serious progress in the right direction.

By a voice vote, and with only a single Republican asking to go on record in opposition, the committee approved a measure, proposed by its Democratic chairman, Patrick Leahy of Vermont, that would significantly enhance the privacy protection given to emails.

The bill, an amendment to the outdated 1986 law that now governs email access, the Electronic Communications Privacy Act, would require law enforcement agents to get a search warrant from a judge in order to obtain email content from a communications service provider that holds private electronic messages, photos and other personal records, like Gmail or Facebook. This means having to show the court there is probable cause to believe that the sought-after records may reveal evidence of wrongdoing.

The approach embraces a sound principle: Private electronic correspondence stored with an Internet company in the “cloud” should receive the same protection afforded letters, photos and other private material stored in a drawer or filing cabinet, or on a computer at home.

Under current law, the warrant requirement is largely limited to emails that are less than 180 days old. For other emails and digital files, investigators may obtain a court order based on a lower legal standard, showing only that the material is “relevant” to an investigation. In many cases, prosecutors can, without any judicial involvement, issue a subpoena demanding to see messages held by third parties.

Of course, some law enforcement officials oppose tighter restrictions on email access. But nothing in the bill would prevent law enforcement from doing its job or change exceptions in existing law for acting without a warrant in emergencies, when time is of the essence.

The committee measure is limited in scope; most notably, it includes no new protections for location information from cellphones or GPS systems that can be as revealing of a cellphone owner’s associations, activities and personal tastes as listening in on a conversation, for which a warrant is required.

Although the bill is not expected to advance in this lame-duck session, it sets the stage for further debate and action on digital privacy in both the Senate and the House early in the new Congress.